Question: Equation of a plane

Write the equation of a pane (P) which passes through the point E(2,1,0) and F(1,2,1) such that distance from the point A(1,-2,-1) to the plane (P) twice distance from the point B(2,4,3) to the plane (P).

My main idea is based on, if the line (d) passes through the points A and B and cuts the plane (P) at the point M, therefore d(A, P)/d(B, P) = AM/BM, where d(A, P) is distance from the point A to the plane (P). And this is my code.

restart;

with(geom3d);

point(A,1,-2,-1);

point(B,2,4,3);  

OnSegment(C, A, B, 2);

coordinates(C);

point(E,2,1,0);

point(F,1,2,1);

Equation(plane(alpha,[C,E,F],[x,y,z]));

OnSegment(T, A, B, 3/2); 

coordinates(T);

Equation(plane(beta,[T,E,F],[x,y,z]));

Please comment on this code. Thank you very much.